EW YORK - A new vaccine protects children from some, but not all, ear infections, according to results of a Finnish study. The researchers estimate that the vaccine could prevent 1.2 million of the 20 million middle ear infections that occur in the US every year.

Middle ear infections, also known as otitis media, are common in young children, with 60% developing one before their first birthday. Nearly one in five doctor visits by preschoolers are for acute otitis media.

Otitis media can cause temporary hearing loss, while repeated ear infections can damage hearing permanently.

The Food and Drug Administration approved the vaccine used in the study, called Prevnar and made by Wyeth-Ayerst Laboratories, last year. Prevnar contains seven strains of the bacterium Streptococcus pneumoniae, an organism responsible for between 28% and 55% of all cases of acute otitis media.

In the February 8th issue of The New England Journal of Medicine, Dr. Juhani Eskola of the National Public Health Institute in Helsinki and colleagues reported on a trial of the vaccine, which included 1,662 babies. Children were given Prevnar, or a hepatitis B vaccine as a control, at two, four, six, and 12 months of age.

During the follow-up period, which lasted until the children were two years old, there were 2,596 cases of otitis media.

Children who received Prevnar had 57% fewer infections with the strains of bacteria included in the shot. The vaccine also reduced infection with related strains of bacteria by 51%. It cut infections with any type of pneumococcal bacteria by 33%.

The researchers found that children given Prevnar were also less likely to develop infections requiring hospitalization. While there were four such cases in the Prevnar group, 13 children in the control group required hospitalization for infection.

And while only one child who received Prevnar developed an invasive infection with pneumococcal bacteria, three children in the control group did.

Otitis media can spread in rare cases to the inner ear, causing dizziness and balance problems. It can also infect the membranes surrounding the brain. This infection, called meningitis, can be fatal. The invasive infections seen in the study included meningitis and spread of bacteria to the bloodstream.

A number of bacteria and viruses can cause ear infections, and the vaccine was unable to guard children from all of them. However, the shot reduced overall ear infections by 6%.

The researchers conclude: "On the basis of our data, we calculate that up to 1.2 million of the 20 million yearly episodes of acute otitis media in the United States could theoretically be prevented if the vaccine were widely used. Moreover, the vaccine also helps to prevent invasive infections and pneumonia due to S. pneumoniae." (Reuters Health)

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